I have an old N64 that when put away worked fine.
I got my 12 year old to clean up a bunch on junk on the promise that he could play it again. We have a Wii but he loves the old Mario64.
Anyway when I plugged it into an tube TV. I got a bunch of green horizontal noise and then black. I'm assuming the TV gave up trying to find the signal.
howtomendit.com for free repair help, information and advice.